Flaviviruses

Question 1

Where was yellow fever most prevalent

Answer 1

when the panama canal was getting constructed

Question 2

How was yellow fever transmitetd

Answer 2

by mosquities
aedes egypti

Question 3

how did people discover how yellow fever was getting transmitted

Answer 3

they recruited volunteers and paid them

Question 4

what is the type of virus of yellow fever

Answer 4

flaviviruses

Question 5

What put an end to human experiments

Answer 5

clara maass a nurse that got paid for be bitted by yellow fever mosquitoes and she got killed

Question 6

Mosquito brigades

Answer 6

• Colonel Gorgas arrived in Panama as the Chief Medical Officer (1904)
• Discoveries linking mosquitos with malaria
• Decides to act on possibility that insects could be transmitting yellow fever
• In 1905: “mosquito brigades”
  -campaign to fumigate and eradicate the disease
• By Aug 1906, there were just 7 cases of yellow fever along the Panama canal

Question 7

Control of yellow fever

Answer 7

In 1915, the Rockefeller Foundation funded a project to eliminate breeding places for Aedes aegypti in areas where yellow fever was prevalent

Question 8

why was yellow fever nor eradicated?

Answer 8

-transmission cycle is complicated
-humans get the disease from mosquitoes
-there is a third reservoir: monkeys

Question 9

facts about the flaviviridae family

Answer 9

• Flavus (Latin = yellow)
• type virus: YFV
• Enveloped viruses
• Icosahedral capsid
• 40-60 nm in diameter
• Genome: (+) ssRNA
• monopartite, linear
• 9.6 -12.3 kb in length

Question 10

JEV is part of which virus fam

Answer 10

flaviviridae

Question 11

true or false: JEV is transmitted by mosquitoes

Answer 11

true

Question 12

Hosts of JEV

Answer 12

• Primary hosts: birds, pigs
• Incidental/dead-end hosts: humans

Question 13

Symptoms of JEV

Answer 13

• Symptoms: fever, headache, vomiting,
  neurologic symptoms (mental status,
  movement disorders, etc)

Question 14

true or false: there is a vaccine for JEV

Answer 14

true

Question 15

Encephalitis Viruses facts

Answer 15

• Majority are asymptomatic or cause
  nonspecific febrile illness
• Primarily affects children or young adults
  (0-15 yrs old) but west nile is older people
• More severe cases:
• Meningoencephalitis
• Aseptic meningitis
• Polio-like acute flaccid paralysis
• “Parkinsonian” syndromes (tremor,
  cogwheel rigidity, masklike facies)

Question 16

how can you get west nile

Answer 16

culex mosquitos

Question 17

host of west nile

Answer 17

• Primary hosts: birds
• Incidental/dead-end hosts: humans, other
  mammals

Question 18

who gets west nile virus

Answer 18

Primarily elderly/immunocompromised

Question 19

symptoms of west nile virus

Answer 19

Symptoms: fever, headache, vomiting, muscle
weakness, lower back pain, neurologic symptoms (loss
of motor function, encephalitis, meningitis)

Question 20

true or false: the is no vaccine for west Nile virus

Answer 20

true

Question 21

true or false: most of the cases of west nile are symptomatic

Answer 21

false they are mostly asymptomatic

Question 22

How can you get dengue

Answer 22

Arbovirus, transmitted by
Aedes mosquitos (Aedes
aegypti and Aedes albopictus)

Question 23

What are the primary host of dengue

Answer 23

human

Question 24

symptoms of dengue

Answer 24

Fever, headache,
vomiting, abdominal pain, low
blood pressure, tachycardia,
seizures, encephalitis

Question 25

True or false: there are no vaccines for dengue

Answer 25

true

Question 26

True or false: mostly kids get dengue

Answer 26

false there is no age distingtion

Question 27

How many subtypes of dengue are there and how are they spreaded our

Answer 27

there are four and they are all spreaded out over the world

Question 28

where is zika the most prevalent?

Answer 28

in south america

Question 29

how is zika spreaded

Answer 29

Arbovirus, transmitted by Aedes mosquitos (primarily Aedes aegypti)

Question 30

What are the symptoms of zika

Answer 30

Symptoms (20%): fever, maculopapular rash, headache, joint and muscle plain, edema, vomiting

Question 31

when was the last outbreak of zika and what happenend

Answer 31

Recent outbreaks (2013- Present): Guillain-Barré syndrome and fetal microcephaly

Question 32

True or false: there is no vaccine for zika

Answer 32

true

Question 33

what are the necessities to tackle an emerging virus

Answer 33

-model systems -diagnostics -vector control -therapeutic strategies

Question 34

true or false: flavivirus encode for a polyproteins

Answer 34

true

Question 35

which +ssrna virus had an immature and a mature configuration

Answer 35

flavivirus

Question 36

Virus entry: flavivirus

Answer 36

* E protein mediates attachment to receptor * in late endosome, low pH —> E protein conformational change * sticks into endosomal membrane * results in fusion

Question 37

What does facilitate flavivirus replications

Answer 37

genome circularizatio

Question 38

what is the ration of + and - strand during replication?

Answer 38

there is always more + strands that are being made than - strands

Question 39

Flavivirus replication results in sfrnas

Answer 39

* produced by XRN1 stalling on RNA knots in 3’UTR * inhibit antiviral responses in both hosts * type I IFN response in mammals * RNAi pathway in mosquitos * modulate cytopathic effects and cell death in mammals

Question 40

what is srn-1

Answer 40

host exonuclease that degrades uncapped RNA

Question 41

How did flaviviruses have to adapt to 2 hosts

Answer 41

* ie. conserved deletions in DENV 3’UTR upon mosquito- adaptation * disrupts one of the XRN1- resistant structures * leads to different primary sfRNA species * increased fitness in mosquitos, reduced in humans * reversion of deletions when re-adapted to humans

Question 42

Infection involves a diverse population of viruses: flavivirus mutations

Answer 42

-the virus mutates a lot * flavivirus RdRp’s introduce 1 mutation per new strand on average * each new host/tissue/cell type will create different selective pressures * ie. in mosquitos: * virus must first escape gut * virus must eventually enter salivary glands

Question 43

True or false: flavivirus replication induces vps and cms

Answer 43

* DENV induces rough-ER- derived vesicle packets (VPs) and convoluted membranes (CMs) * Sites of replication * Vesicles have pores (presumed exit site for newly synthesized viral RNAs)

Question 44

Flavivirus assembly sites

Answer 44

* Budding viruses can be observed next to the pores of VPs * Virions stack within the lumen of the VP- containing ER network * Virions egress through the Golgi

Question 45

how does flavivirus matures

Answer 45

the host furin will cleave the PrM into the M protein so that it is able to fuse with the host membrane

Question 46

DENV Antibody-dependent Enhancement

Answer 46

* Increased severity of secondary infections * Antibodies from 1º infection recognize different serotypes weakly and facilitate DENV binding and internalization - Leukocytes and BBB cells (= encephalitis) - Inflammation and cytokine secretion (cytokine storm) - Compromises CNS function